Metal oxides with nanometer size have attracted much attention in the fields of electrochemistry, biomedicine and other sciences due to their excellent catalytic properties. At present, the traditional methods of preparing metal oxide nanoparticles include the hydrothermal method, solthermal method, precipitation method, microemulsion method, sol-gel method and template method. However, the development of these methods is limited due to the high cost and the existence of residual organic solvents. Therefore, it is urgent to develop a new preparation techno-logy of metal oxide nanoparticles to make up for the shortcomings of traditional methods and promote the development of preparation technology of metal oxide nanoparticles. Supercritical fluid is a kind of fluid in a special state whose temperature and pressure are above the critical temperature and pressure of material. It has some properties of gas and liquid. It has unique solvation characteristics, near zero surface tension, low viscosity, easy to adjust, close to the density and solubility of liquid and similar gas diffusion properties. In recent years, the supercritical fluid technology has garnered enormous interest in chemical, environmental, pharmaceutical and other fields due to the mild operation conditions and unique properties of supercritical fluids (SCFs). Amongst different variants of SCF processes, the supercritical anti-solvent (SAS) method is widely used in the fabrication of nanoparticulate forms of various substrates as its moderate operating condition, results in no residual organic solvents in the particles, and controllable particle size among others. Various metal oxide nanoparticles can be synthesized using this SAS process, which showed excellent applications in various fields, such as catalysis, sensing, and biomedicine. In this article, the basic principle, preparation process and application of diverse metal oxide nanoparticles by the SAS method are reviewed. In addition, the effects of temperature, pressure and solution concentration in SAS process on the size and morphology of metal nanoparticles were also discussed. And we also emphasized the challenge that may affect the application and future development. © 2022, Materials Review Magazine. All right reserved.
